Pressure responsive regulator



y 3, 1952 H. SEELER 2,596,178

PRESSURE RESPONSIVE REGULATOR Filed Oct. 12, 1948 2 SHEETS-SHEET 1INVENTOR. .//f/V/ .5 154? May 13, 1952 H. SEELER Filed Oct. 12, 1948'EIEI 2 SHEETS-SHEET 2 INVENTOR. HENRY 555 :5?

ATTORNE/ Patented May 13, 1952 UNITED STATES PATENT OFFICE' Claims.

(Granted under the act of March 3, 1883, as amended April 30.. 1928; 3700. G. 757) The invention described herein may be .manufactured and usedby or for the United States Government for governmental purposes withoutpayment to me of any royalty thereon.

The present invention relates to a pressure responsive regulator orrelay for use in oxygen demand breathing systems or analogous gas flowregulating systems.

The primary object of the invention is to pro-. vide an oxygen demandregulator in which the flow of oxygen is controlled by a valve which isactuated by means of the high pressure oxygen supply and in which thepressure actuating means is in turn made responsive to a pilot valveactuated through a diaphragm exposed on one side to breathing pressures,and on the other side to atmospheric pressures.

A further object of the invention is to provide an oxygen demandregulator of general application in oxygen demand systems andcharacterized by a control diaphragm subject to atmospheric pressure onone side and to breathing pressure on the other side, whereby thediaphragm may act through a secondary or control valve to operate aprimary or oxygen flow valve to supply oxygen to a subject when heinhales and to out ch such oxygen when he exhales.

Another object of the invention is to provide an oxygen demand regulatorfor use at high altitudes and including means responsive to thedecreased atmospheric pressures at high altitudes to increase the flowof oxygen to the subject relying on the regulator to supply oxygen.

Another object of the invention is to provide a sensitive oxygen demandregulator of compact form and including a secondary or control valvewhich fits within a main or primary valve in telescopic relation, andincluding a sensitive diaphragm adapted to actuate the control valvethrough a lever system and further including another diaphragm adaptedto actuate the main valve to regulate the flow of oxygen to a face maskor other breathing appliance.

Another object of the invention is to provide an oxygen demand regulatorincluding a secondary or control valve adapted upon actuation to causeoperation of a main or primary valve to regulate the flow of oxygen andwherein the secondary and primary valves are each arranged to have nofluid pressure thereon tending to unseat the valves in the closedposition.

Another object of the invention is to generally improve theefiectiveness and reliability of oxygen demand regulators for use withoxygen demand breathing systems.

The above and other objects of the invention will become apparent uponreading the following detailed description of the invention inconjunction with the accompanying drawings, in which:

Fig. 1 is a vertical cross sectional view taken through one form of thepresent oxygen regulator and showing also the connection thereof to oneform of face mask which may be used with the regulator.

Fig. 2 is atransverse cross sectional view taken on the line 2-2 of Fig.1.

Fig. 3 is a vertical cross sectional view taken through another form ofoxygen regulator embodying certain refinishments over the device of Fig.1.

In oxygen demand breathing systems there is usually provided some meansto regulate or meter the flow of oxygen to the breathing mask orapparatus. If the regulator is made responsive to periodic reduction ofpressure inside the mask then it may be made to increase the flow ofoxygen in accordance with the reduced mask pressure and thus supplyoxygen when there is .a demand for it. This type of control systemresults in conservation of the oxygen supply and also ensures a minimumof discomfort and effort during breathing. Such a system-including alsomeans to utilize air as well as oxygen for breathing, is disclosed andclaimed in my copending application Serial No. 50,343, filed September21, 1948, and entitled Oxygen Demand Breathing System Including MeansFor Altitude Regulation, which has matured into Patent No. 2,552,595 oiMay 15, 1951. The uses and functions of the present regulator will beexplained as the description proceeds but the constructional features ofthe regulator will be stressed especially.

Considering first the regulator or demand relay of Fig. 1 it is seenthat the housing of generally circular shape comprises the upper and.lower housing elements I and 2, with the upper element threading intothe lower at 3. An internal shoulder of the housing element 2 receives athin flexible diaphragm 4, which is .clamped in place by the upperhousing element I as shown. This diaphragm is preferably made of a high-,strength rubberized texile fabric about 0.015 of an inch thick and inone example of the present regulator is only one and one-half inch indiameter. The diaphragm 4 divides the housing interior into an upper oraneroid chamber and a lower or control chamber. The upper chamber isopen to the atmosphere by way of holes 5 in the housing element I.Centrally located on the upper wall of the housing element l is a boss 6apertured and tapped to receive a threaded stem I, which may be adjustedvertically and. then looked in any adjusted position by means of a locknut 8. The stem 1 carries an aneroid bellows 9 having a spring supportII) on its lower end face. Extending between the support I and thecenter of the diaphragm 4 is a light spring II under compression. On theunderside of the dia phragm 4 there is a central pressure plate I2contacted by a lever I3 pivoted to the housing at I I. Near its pivotedend the lever I3 contacts one end of a second lever I5, which is pivotedat I6 to a bracket I6 secured to the housing element 2. The inner end ofthe lever I extends to the central axis of the regulator structure whereit connects, with a control or pilot valve II, which has a stem looselyfitting a hole near the end of the lever I5.

Secured within the housing element 2 by means of a threaded ring I8 is asecond diaphragm Ill, which is considerably thicker and less sensitivethan the control diaphragm i. A suggested thickness for the diaphragm I9is 0.08 of an inch and as before it may also be made of a rubberizedtextilesheet material. Centrally the diaphragm I9 is apertured toreceive a sleeve 26 forming the upper portion of an oxygen supply valve20. The diaphragm I9 and the sleeve are clamped in assembled relation bymeans of a clamping ring 2! threaded over the upper end of the sleeve20'. Threaded into the upper end of sleeve 20 is a valve guide 22, inwhich the control valve [1 is slidably mounted. The lower end of valveI'I. carries a poppet element and situated between the poppet and thevalve guide 22 is a coil spring 23 tending to hold the valve II inclosed position. To prevent leakage between the valve I! and the'valveguide 22, there is provided a rubber band 24 encircling both the stem ofvalve I1 and a downwardly extending portion of guide 22. Gas pressurewithinthe valve 20 serves to maintain the sealing action of the band 24but the band is normally under tension in any case, whether there isfiuid pressure in the valve or not. Through the walls of sleeve 20'there are provided several passages 25 opening into a thin chamber belowdiaphragm I 9, whereby pressure may be aplied to lift the diaphragm andthe oxygen supply valve 20. Furthermore the primary valve chamber orpilot chamber below the diaphragm I9 is open to the atmosphere by apinhole passage 26 to allow the pressure in the chamber to return toatmospheric when flow through the passages 25 has stopped. The pilotvalve I1 and oxygen supply valve 20 may be termed the secondary oxygenvalve and the primary oxygen valve respectively.

The main portion of valve '29 is provided with a central valve passage21 the upper end of which provides a seat for the poppet element ofvalve I'I. Secured in thelower end of valve 25! is gasket 23 "Whichlsalso apertured in alignment with the passage 21. The gasket 28 isadapted to contact the valve seat 29 provided on the bottom wall of an.oxygen supply chamber 30. The enlarged lower end of the valve 20 isguided within the chamber 30 but has four sides cut away to provideoxygen supply passages, as best shown in Fig. 2. The central portion ofvalve 29 is guided by means of a bushing or guide 3| fixed in thehousing element 2. A compression spring -32 is in contact both with theguide 3| and the enlarged lower end of the valve 20. In engagement witha portion of the guide 3| and the central portion of the valve 20 is arubber sealing band 33, which functions just like the band 24 describedabove.

Extending through the bottom wall of the chamber 30 is an oxygen passage29' opening centrally of the valve seat 29 into the chamber 30. Theoxygen passage 29' and the gas receiving spaces therebelow may be termedthe gas inlet chamber.

The lower end of the housing element 2 is provided with a cylindricalrecess to receive a porous filter 34, which is held inposition by a coilspring 35 and a threaded retaining ring 35. An extension of the housingelement below the filter chamber provides a fitting element 3'! of anydesired form for attachment to an oxygen bottle or conduit. The filter 33, which is recessed centrally at 34, acts to strain out dust or foreignmatter which might be harmful to the regulator mechanism especially ifit lodges on the valve seats. The filter may be made of various porousmaterials, such as ceramic or metallic materials. The porous metalfilters, which are preferred for their durability, are made by sinteringa mass of powdered metals which braze themselves into a metallic networkporous enough to pass oxygen gas and filter it free of foreign matter.Such a metallic filter might be produced in accordance with theprinciples set out in U. S. Patent No. 2,297,817 granted to Clyde W.Truxell et al. on October 6, 1942. In direct communication with theoxygen supply chamber 30 is an oxygen supply fitting 38 and incommunication with the control chamber is another fitting 39. Thesefittings are adapted to have rubber connecting tubes secured thereto.

To disclose the preferred use for the present regulator or relay, Fig. 1illustrates an oxygen demand system similar to that of my copendingapplication referred to above. As indicated in Fig. 1 the fittings 38and 39 of the oxygen regulator are connected to a pair of thin flexibletubes es and III respectively, which lead to a face mask 42 worn by asubject 43. Thus the tube 40 carries pure oxygen from the regulator tothe mask, and the tube II transmitsgas pressure to the control chamberof the regulator for effecting a cyclic control action on the fiow ofoxygen to the mask. The mask 42, which covers both the nose and mouth,is fastened securely to the face of subject 43 by straps passing aroundthe head. In the front wall of the mask is an air inlet valve 44 whichis responsive to reduced pressure inside the mask to open and allow airto be taken, in for mixing with oxygen during inhalation phases of thebreathing cycle. The inlet or inhalation valve M comprises a flexibleflapper element 44 normally seated on .a circular valve seat but adaptedto move away from the seat when the pressure in the mask is negative,that is below the atmospheric pressure. Thus during inhalation thesudden reduction of pressure inside the mask causes valve 44 to open andthus permits air to enter the mask. The mask wall also carries anexhaust or outlet valve 45 which is responsive to increased pressureinside the mask to open and allow the products of respiration to beexpelled during exhalation phases of the breathing cycle.- The valve 45includes a thinrigid disk 46 normally held against a circular valve seatby-means ,of a coil spring 41. In Fig. 1 the inlet or inhalation valve44 is shown in open position and the outlet or exhalation valve is shownin closed position. Thus at the instant depicted the subject 43isinhaling and is drawing air from the free atmosphere into the mask andthis air may 'mix with pure oxygen flowing from the oxygentube 40 intothe mask. Since air is about 21 per cent oxygen by volume, the airinhaled provides part of the oxygen requirements of the subject andhelps to conserve his supply of pure oxygen accordingly.

Instead of the flapper-type of air inlet valve made of rubber or otherflexible material it may be preferred in some instances to use otherforms of sensitive valve devices, such as the disk-andspring type ofvalve similar to the outlet valve 45. Since the gas pressures inside themask are kept very low, the inlet and outlet valves are made to respondto small pressure differentials accordingly. For example the criticalpressures for these valves may be five millimeters of water for theinhalation valve 44 and twenty millimeters of water for the exhalationvalve 45. These values of pressure response are only stated by way ofexample but in any case it is understood that the pressure as stated forthe inhalation valve refers to a pressure inside the mask belowatmospheric, While the pressure as stated for the exhalation valverefers to a pressure inside the mask above atmospheric.

The aneroid bellows 9, which affords altitude compensation or regulationand thus ensures an increasing supply of oxygen as the altitudeincreases, is a standard unit. This type of bellows is sealed up whilein a vacuum and has enclosed within the bellows a coil spring. Under thepressure of sea level atmosphere the bellows will be compressed amaximum amount and as altitude is increased the bellows will expand inproportion to the increase in altitude. The spring within the bellowsovercomes the bending resistance of the metal bellows walls, thus makingthe bellows more sensitive.

The operation of the system as shown in Fig. l

will be explained to show how the regulator functions to respond to theoxygen demand of the subject 43. For the first part of the explanationit is assumed that the system is in use at about 12,000 feet above sealevel. The subject 43 may now inhale and the reduction of pressureinside the mask will immediately cause the air inlet valve 44 to openfor admission of air into the mask. Simultaneously the pressure in thecontrol chamber of the regulator will be reduced by virtue of theconnecting tube 4|. With the pressure below the diaphragm 4 reduced, theair pressure on the upper side of the diaphragm will cause the controldiaphragm to bulge downward- 1y to effect opening of the control valve l1 by action of the levers l3 and [5. Now oxygen may issue from thepassage 21 into the hollow valve and thence by way of the passages intothe space below diaphragm I9. Since the oxygen pressure is much greaterthan the low pressure above the diaphragm I9, the diaphragm and theattached valve 2!! lift to thus open the oxygen supply valve and admitoxygen to the chamber 30. The oxygen now flows through the fitting 38and tube into the mask, Where it mixes with the air flowing into themask through air inlet valve 44. This mixing action is usually referredto as oxygen dilution but its purpose is to increase the proportion ofoxygen in the air being breathed. At the moderate altitude underconsideration the aneroid 9 is not expanded enough for the spring H tohave any appreciable effect on the control diaphragm. Under the altitudecondition stated, the gases inside the mask during inhalation phaseswill now be sufliciently enriched by oxygen to give a suitable breathingmixture. The air being at a reduced atmospheric pressure there will beless oxygen per unit volume than at low altitudes and an oxygensupplement will be necessary. Now when the subject exhales,

the valve 44 will close while the valve 45 will open to allow theproducts of respiration to be expelled into the atmosphere. Moreover thepressure increase inside the mask will be transmitted to the controlchamber of the regulator and the control diaphragm 4 will be forcedupwardly. With the downward pressure on lever l3 relieved, the spring 23will cause the control valve I I to close, and the pressure underdiaphragm [9 will soon be reduced to atmospheric because of the bleedpassage 26. The coil spring 32 will now act to close the oxygen supplyvalve 20 and thus conserve the oxygen which is available in limitedquantity. From the description of operation it will be seen that air isused to as great an extent as possible but is diluted with oxygen as thedemand therefor is made to operate the regulator. Using the oxygen onlyas a supplement helps to conserve the limited supply which is carried onthe aircraft. During exhalation phases of breathing the regulator actsto close the oxygen valve and prevents further flow of oxygen whilethere is no demand therefor. It is further noted that the regulatingaction of the device does not involve high pressures, because of therelay principle embodying the pilot valve I1 and the thin diaphragm foractuating the valve by way of levers I3 and H3. The oxygen pressureavailable is used to open the supply valve 20 and is thus used to goodadvantage in opening the main valve in accordance with concurrent actionof the pilot or control valve IT. The subject is therefore able toregulate the cyclic flow of oxygen merely by exerting normal inhalationand exhalation pressures, which in turn efi'ect control of the oxygenvalve 20 by means of the diaphragm 4 and the pilot valve H. The valve llby its relay action thus controls the flow of oxygen to thehigh-pressure chamber below the valve actuating diaphragm l9.Furthermore the ele ments which must be actuated by the thin diaphragm 4are light in weight and therefore have little inertia to retard theiraction. A further advantage inherent in the present regulator is thatthe device may be made small in size and light in weight. The size maybe gagedi by the fact that in one completed regulator the controldiaphragm 4 is only one and one-half inch in diameter.

Considerin now the action of the oxygen demand system and regulator at aconsiderable altitude, for example about 22,000 feet above sea level, itis first noted that the aneroid bellows S will. be slightly elongatedcompared to its length as in the previous example. Now the coil springit will be compressed to a greater extent than before and the resultantincreased force exerted on the control diaphragm 4 and on the levers l3and [5 will act to hold the control valve ll slightly open even thoughthe sube t 413 is not inhaling nor exhaling at the moment. With thevalve I! open the pressure build-up in the pressure chamber underdiaphragm H3 will act to hold the oxygen supply valve 2:; off the valveseat 29 and thus allow oxgyen to flow through the chamber ti) and tubeas into the face mask 42. Now when the subject inhales, the reducedpressure in the control chamber will cause the diaphragm 4 to movedownwardly still farther under the force of spring H and atmosphericpressure acting on top of the diaphragm. The response of levers l3 andi5 and valve I! will cause a more definite elevation of the oxgyensupply valve 20 and a consequent plentiful supply of oxygen to the face7 mask through. the tube 40.7 The tube 40 acts also to reduce thepressure of oxy en as delivered to the mask. While the oxygen pressurein the chamber 30 may be considerable, the throttling effect of thesupply tube 40 and the'large volume available in the mask and lungs ofthe subject ensure that the mask pressures will not be excessive. Withthe present system a suggested initial pressure at the neck of theoxygen bottle is 400 pounds per square inch. Oxygen is usually suppliedfrom a bottle or cylinder of the compressed gas although it is possibleto use liquefied oxygen or an oxygen generator. At the higher altitudeunder consideration presently the air inlet valve 44 will openduringinhalation but will not open fully nor for all of the time takenup by the inhalation phase, since there is a slightly increased pressureinside the mask due to the more pronounced opening of the oxygen supplyvalve 20. Thus the proportion of air inside mask will be less than atthe lower altitude discussed above. For example at 22,000 feet the maskcontents during inhalation may be 80 per cent pure oxygen and 20 percent air. Thus it is seen that as the altitude is increased and the airinlet valve 44 opens less, the extent of oxygen dilution of the airbeing breathed will be increased in proportion' Upon exhalation thevalves l1 and 20 will close, by reason of the pressure increase withinthe control chamber of the regulator. When thefpilot valve I? closes andoxygen no longer can reach the chamber under diaphragm iii, the pressuretherein will be reduced to atmospheric by reason of the bleed passage26.

Operation of the regulator at extreme altitudes, for example at 35,000feet above sea level, differs from that explained above mostly in thefurtherelongation of the aneroid bellows 9 and the further compressionof the coil spring ll. Under these conditions of reduced atmosphericpressure the force of the spring II is the main influence in openingthec-ontrol valve H. The lack of atmosphericpressure on the upper sideof the control diaphragm 4 as well as the higher pressures under thediaphragm due to increased oxygen flow will mean that during inhalationthe diaphragm 4 will not have any marked tendency to bulge downwardly.The main force effective in opening the control valve l1 and the oxygenvalve 20 will be the bellows 9' and the spring H and it should be notedthat this will be a constant force at a constant altitude. Thisactuating force now being at a maximum, the assisting forces or thecounter forces will not have much effect unless they too are increasedin magnitude. However since these forces developed during the breathingcycle by the action of the subject will not increase materially athigher altitudes, the bellows is the main factor at the extremealtitudes. Because of the bellows action the valves I1 and 20 will nowbe held open at all times except during exhalation, and

as a result the pressure inside the mask will tend to increase from theinflux of pure oxygen from the regulator. The subject may now inhalewith less effort and the inhalation phases will not bring about anyopening of the air inlet ,valve e4. Thus he will now be breathing pureoxygen at all times. As he exhales there will be an increase in gaspressure inside the mask and the outlet or exhaust valve 45 will open torelease most of the expelled respiration products. The pressure increasewill be transmitted to the control chamber of the regulator by means ofthe tube 4| and the diaphragm 4 will accordingly bulge upwardly. Theresulting action will cause the control valve [1 to seat and therebycause seating of the oxygen supply valve 20. Thus as the demand isremoved the oxygen supply is cut off and oxygen thereby conserved forthe inhalation phases of breathing.

In passing it is noted that there are varying pressures on the oppositesides of the diaphragm I9 but they are of such differences in magnitudethat variations in pressure above this diaphragm during the breathingcycle may be ignored entirely. The only important consideration as faras the operation of the diaphragm I9 is concerned is the rise and fallof'the oxygen pressure under the diaphragm as the control valve I1 isopened and closed. Also while the control chamber is connected to themask by tube 4| the tube has some pressure reducing effect, but in anycase the control pressure will always be in direct proportion to thepressure inside the face mask 42.

One possible breathing system has been described abcve using the presentregulator, but there are other possible systems where the regulator maybe equally effective. For instance the system of Fig. 1 may be modifiedby omission of the air inlet valve 44. Such a system would operate quitewell as an oxygen demand breathing system where no outside air is to beused. A system of this type might be used in high altitude flying tosupply oxygen to aircraft personnel or it might be used Wherethe-outside air is contaminated by fumes or dust, such as in unsafemines or in case of air pollution by gas, smoke or dust. Therefore itshould be understood that the regulator as disclosed, as well as similarforms of the device, are adapted for usein a variety of situations andwith a variety of associated devices such as masks, inhalators andhelmets. While the regulator has been described and illustrated asthough it were always maintained in a vertical position, it should beunderstood that operation will be satisfactory in other positionsthereof. In fact when in use on aircraft it must function during variousflight maneuvers and must be able to withstand sudden changes inposition and still continue to function.

For a detailed description of a second regulator embodying certainrefinements and advantages over the device of Figs. 1 and 2 reference ismade to Fig. 3 of the drawings. In the second form of the regulator ahousing is provided which is of circular shape in cross section and madeup of upper and lower housing elements 5| and 52, with the upper elementthreading into the lower at 53. An internal shoulder of the housingelement 52 receives a thin flexible'diaphragm 54, which is clamped inplace by the upper housing element l as shown. This diaphragm is ofhighstrength rubberized textile fabric like the diaphragm 4 of Fig. 1.Also clampedin place over the diaphragm in contiguous relation theretois a thin metal disk or safety plate 54' having a central circularopening therein. The diaphragm 54 divides the housing interior into anupper or aneroid chamber and a lower or control chamber.

The upper chamber is open to the atmosphere by way of holes 55 in thehousing element 5|. Centrally located in the upper wall 'ofthe housingelement 5! is a tapped opening 56 which receives a threaded stem- 5?.The stem 51 may beadjuSted vertically and then locked in place by meansof a lock nut '58. The 'stem 51 carries an'aneroid bellows 59 having aspring support 60 on its lower end face. Extending between the support60 and the center of the diaphragm is a light coil spring (H, whichbears on a circular plate 6| cemented to the diaphragm. On the undersideof the diaphragm 54 there is a central pressure plate 62 having anoutside diameter greater than the diameter of the opening in safetyplate 54. The pressure plate 62 contacts a lever 63 which is pivoted at64 to a fixed support 66. The lever 63 contacts another lever 65 whichis pivoted at 66' to the support 66. The inner end of the lever 65extends to the central axis of the regulator structure where it connectswith a control or pilot valve 61, which has a stem loosely fitting ahole near the end of the lever 65.

Secured within the housing element 52 by means of a threaded ring 68 isa second diaphram 69, which is considerably thicker and less sensitivethan the control diaphragm 54. Centrally the diaphragm 69 is aperturedto receive a flanged cup 10, secured to the diaphragm by a threadedclamping ring H. Threaded into the cup 70 is the valve member 72 havingconnected thereto an oxygen valve 13 carrying a seating gasket 73' onits lower end. Between the top wall of cup l and the upper end of valvemember 72 there is a valve guide 14, and extending between the guide andthe enlarged lower end of pilotvalve 61- is a coil spring 15. A rubbersealing band is also employed in a manner similar to the band 24- ofFig. I, so as to prevent gas leakage around the stem of valve 61. A seatfor the valve 67 in the member f2 opens into passages 16 extendinglaterally in. a thin chamber under the diaphragm 69. The chamber in turnopens to the atmosphere by way of a pinhole 11, for permitting thepressure to return to atmospheric after oxygen flow into the chamber iscut off. The valve 13 has a central passage therein opening laterally atT8 to the oxygen chamber 79. At the upper end of this central passagethere is a recess which connects by passages 80 to the interior of valvemember 12, in order to complete the passage for oxygen into the chamberunder diaphragm 69 when the valve 61 is unseated. Of course the passages16 and 80 are so located in valve member 12 that they do not intersectwith each other. It is noted that the stem of valve 61 is the samediameter as the seat for the valve and therefore with the pilot valveclosed the oxygen pressure will be'distributed around the valve evenlyand there will be no force from the gas pressure tending to open thevalve. Once the valve is opened by action of the diaphragm 54, lever 63and lever 65 there will be some endwise gas pressure tending to hold thevalve open. This force is opposed by the spring 75 so that the gaspressure is thus resisted by a force that increases as the valve opensfarther. In any event the spring 75 will be made strong enough to closethe valve 61 as soon as the actuating force of the diaphragm and leversis diminished.

The oxygen valve 13 is guided by contact between the lower end portionand the walls of chamber I9 and also by means of a guide member 8| heldin place by a threaded clamping ring 82. Between the guide member BI andthe lower end portion of the valve 13 there is a coil spring 83 tendingto close the valve. The disk '84 under the valve carries a valve seat 35having the same diameter as the stem of valve 13. The disk 84 is held inposition as shown by a fitting 86 threaded into the housing element 2and also retaining a screen 81 in place to prevent entry of foreignmatter, particularly during shipping of the regulator. The fitting 88 isshaped on its free end for retaining a flexible tube to conduct oxygento the face mask. Another fitting 81 threaded into housing element '52is shaped to retain a flexible tube leading to the face mask. Thesetubes are not shown but it is understood that they would correspond withthe tubes 40 and 4| of the oxygen demand system shown in Fig. 1.

Threaded into the housing element 52 is a third fitting 88 forconnection with a source of pure oxygen gas under pressure. At the innerend of the fitting 88 is a. gas filter '89 similar to the filter 34 ofFig. 1. To holdthe filter in position without placing it under excessivestrain a coil spring 90 is provided as shown. A recess 89- at the innerend of the filter registers with an opening 9| leading into the oxygenchamber 19.

Attention is again directed to the fact that the valve seat 85' has thesame diameter as the stem of oxygen valve 13. Therefore in the closedposition of the valve the oxygen gas pressure in the chamber 19 will beevenly distributed around the valve 13 so as to exert no initial openingpressure. The valve when closed will thus be stable and not have atendency to open itself with every jar or change in position of theregulator. As explained with respect to the pilot; valve 61, the valve13 after being opened has more gas pressure thereon in an openingdirection than in a closing direction. However on opening the spring 83is compressed more and tends toovercome the opening pressure of the gas.It should be understood that the spring 83 must be strong enough toclose the valve 13 once the oxygen pressure under the diaphragm 69 hasbeen reduced to atmospheric by closing of the pilot valve 61.

The operation of the regulator or pressure relay as shown in Fig. 3 issimilar in all essential respects to the regulator of Fig. 1. Assumingthe regulator of Fig. 3 to be connected in an oxygen demand breathingsystem as in Fig. 1, with fittings 85 and 81 being connected. to theface mask and fitting 88 connected to oxygen gas under pressureno oxygenwill be flowing into the mask. However if the subject inhales thereduced pressure in the mask and in the control chamber of the regulatorwill cause the diaphragm 54 to bulge inwardly under the pressure ofspring 6| and also the pressure of the outside atmosphere. Therefore thelevers 63 and will be actuated to lift the pilot valve 61. Oxygen underpressure will now flow through passages into the valve member 12, thencepast the valve seat into the passages 16 and into the chamber under thediaphragm 69.. This pressure will now lift the diaphragm and parts fixedthereto thus opening the oxygen valve 13 and allowing oxygen to flowpast the valve seat into the fitting 86 leading to the face mask. Onexhalation the pressure in the control chamber rises, pushing thecontrol diaphragm 54 upwardly and allowing pilot valve 61 to close underthe action of coil spring 15. The pressure under diaphragm 69 now dropsto atmospheric because of the bleed passage 11 and as a result theoxygen valve 13 closes under the action of coil spring 83.

The action of aneroid bellows 59 in producing greater flow of oxygen athigher altitudes has already been explained at some length in comnection with Fig. 1 and need not be repeated. It is noted however thatwhen the atmospheric pressure is reduced and the control diaphragm 54tends to bulge upwardly because of higher mask pressure and exhalationpressures, then the diaphragm will be protected from possible 11 ruptureby the safety plate 54. While this plate may be made of thin metal, itis also possible to use a stiff fiber sheet or laminated plasticmaterial which will yield slightly and still not allow the diaphragm toballoon upwardly. It is understood that the stem portions of valves 61and 13 are sealed against leakage where they move in the stem guides byrubber bands as illustrated or by any other suitable or expedient meansavailable. The rubber band sealing means has been found to haveadvantages, since gas pressure around the stem tends to press the rubbertight against the contacting elements. The stems need not slide withrespect to rubber bands, since a limited movement merely results in aflexing of the rubber whereby the bands or sleeves shorten up and bulgeoutwardly in the middle portions thereof.

The advantages and operating results attributed to the regulator of Fig.1 in the detailed description thereof are also inherent in the regulatorof Fig. 3, but in addition the latter device has special features ofconstruction as already described. In particular the regulator of Fig. 3

possesses the balanced valves 61 and 13 having no, gas pressure tendingto open the valves once they are in the closed positions thereof.Another important feature is the protective ring or plate 54 on top ofthe thin diaphragm 54 and having an inside diameter less than theoutside diameter of the pressure plate 62 under the diaphragm. It isalso to be noted that in both regulators described the complete devicesare compact and comparatively simple in construction. By mounting thepilot valve or secondary valve inside of the main valve or primary valvea reliable and compact arrangement is provided, which has the furtheradvantage of symmetry with respect to the central axis of the regulator.Moreover by applying the pilot valve or pressure relay principle to theactuation of the oxygen supply valve, the control diaphragm which isresponsive to breathing pressures may be made small in diameter. At' thesame time demand control over the oxygen supply valve may be exerted bythe normal breathing pressures within the mask. The person wearing themask will not be required to work against cumbersome and unwieldycontrol devices in order to exert demand control over the oxygen supply.Thus one serious objection to some demand control devices is entirelyeliminated. The present regulators, while being quite sensitive forreasons explained above, are also thoroughly reliable and easy tomaintain in good working condition.

The embodiments of the invention herein shown and described are to beregarded as i1 lustrative only and it is to be understood that theinvention is susceptible to variations, modifications and changes withinthe scope of the appended claims.

I claim:

1. An oxygen demand regulator for operative association with a face maskand a container of oxygen under pressure, said regulator comprising amain housing, a control diaphragm extending across said'housing foractuation by the fluid pressure inside the face mask acting on one sideof said diaphragm in opposition to atmospheric pressure acting on theother side of said diaphragm, a second diaphragm in said housingproviding a'supply valve actuating chamber at one side of said seconddiaphragm, means providing a narrow passage from said supply valveactuating chamber to the atmosphere, a pilot 12 valve housing extendingthrough and fixed to said second diaphragm centrally thereof, anextension at one end of said pilot valve housing having a poppet on itsfree end, a circular valve seat in said main housing connectible to saidcontainer of oxygen and cooperating with said poppet valve to provide anoxygen supply valve, an annular oxygen supply chamber within said mainhousing surrounding said extension and having a passageway openingtherefrom for connection with the face mask, a pilot valve movablymounted in said pilot valve housing and cooperating with a pilot valveseat at said one end of said pilot valve housing, passage meansextending through said extension from said pilot valve seat forconducting oxygen from said container to said pilot valve, a wall ofsaid pilot valve housing having therein a passageway leading from saidpilot valve housing to said supply valve actuating chamber, lever meansextending from said control diaphragmto said pilot valve for unseatingsaid pilot-valve by movement of said control diaphragm resulting frominhalation of the person wearing the face mask, whereby oxygen isadmitted to said pilot valve housing and to said supply valve actuatingchamber to thereby unseat said poppet valve by pressure exerted on saidsecond diaphragm to thus supply oxygen to said oxygen supply chamber andto said face mask.

2. An oxygen demand regulator for operative association with a face maskand a container of oxygen under pressure, said regulator comprising amain housing, a control diaphragm'extending across said housing foractuation by the fluid pressure inside the face mask acting on one sideof said diaphragm in opposition to atmospheric pressure acting on theother side of said diaphragm, a second diaphragm in said housingproviding a supply valve actuating chamber at one side of said seconddiaphragm, means providing a narrow passage from said supply valveactuating chamber to the atmosphere, a pilot valve housing secured tosaid second diaphragm centrally thereof, a poppet valve rigidlyconnected to said pilot valve housing, a circular valve seat in saidmain housing and cooperating with said poppet valve to provide an oxygensupply valve, means providing an oxygen passage for connection from saidcontainer to one side of said oxygen supply valve, meansproviding anoxygen passage from the other side of said oxygen supply valve to a facemask connection on said housing, a pilot valve movably mounted in saidpilot valve housing and cooperating with a pilot valve seat at one endof said pilot valve housing, passage means for conducting oxygen fromsaid container to said pilot valve seat, a wall of said pilot valvehousing having therein a passageway leading from said pilot valvehousing to said supply valve actuating chamber, means extending fromsaid control diaphragm to said pilot valve for unseating said pilotvalve by movement of said control diaphragm resulting from inhalation ofthe person wearing the face mask, whereby oxygen is admitted to saidpilot valve housing and to said supply valve actuating chamber tothereby unseat poppet valve by pressure exerted on said seconddiaphragm.

3. An, oxygen demand regulator for operative association with a'facemask and a container of oxygen under pressure, said regulator comprisinga housing, a circular control diaphragm extending across said housing onthe interior thereof and providing an aneroid chamber at one side and acontrol chamber at the other side of said diaphragm, a fiat ring incontiguous and concentric relation with respect to said one side of saiddiaphragm and having its marginal edges fixed to said housing, saidaneroid chamber being open to the atmosphere and having mounted thereinan aneroid bellows and a compression spring in series with the springalso. continuously pressing on said diaphragm, means for making aconnection through a wall of the housing from said control chamber tosaid face mask, means including a second diaphragm for providing aprimary valve actuating chamber in said housing, means providing anarrow passage from said primary valve actuating chamber to theatmosphere, a secondary oxygen valve in said housing to admit oxygenunder pressure to said primary valve actuating chamber, actuating meansfor said secondary oxygen valve including said control diaphragm, aprimary valve actuating means including said second diaphragm responsiveto changes in pressure in said primary valve actuating chamber, and aprimary oxygen valve in said housing including a movable elementattached to said second diaphragm and operable when open to allow flowof oxygen into a portion of said housing having an oxygen outlet openingtherefrom.

4. An oxygen demand regulator for operative association with a face maskand a container of oxygen under pressure, said regulator comprising ahousing, a control diaphragm extending across said housing on theinterior thereof and providing an aneroid chamber at one side and acontrol chamber at the other side of said diaphragm, said aneroidchamber being open to the atmosphere and having mounted therein ananeroid bellows and a compression spring in series for continuouscontact with said diaphragm, means for making a connection through aWall of the housing from said control chamber to said face mask, meansproviding a primary valve actuating chamber in said housing, meansproviding a narrow passage from said primary valve actuating chamber tothe atmosphere, a secondary oxygen valve in said housing to admit oxygenunder pres sure to said primary valve actuating chamber, actuating meansfor said secondary oxygen valve including said control diaphragm, aprimary valve actuating means responsive to changes in oxygen pressurein said primary valve actuating chamber, a primary oxygen valve in saidhousing actuated by said primary valve actuating means and operable whenopen to allow flow of oxygen into a portion of said housing having anoxygen outlet opening therefrom, and means for conducting oxygen underpressure from said container to said secondary and primary oxygenvalves.

5. In a gas demand regulator for regulating the flow of gas to a facemask, a housing including a gas inlet chamber connected at all times toa source of gas under pressure, means at one end of said chamberproviding a circular valve seat, conduit means leading from said valveseat and through a wall of said housing to provide a connection leadingto said face mask, a poppet valve in said chamber having an enlargedpoppet end portion for valve closing abutment at one side thereof withsaid valve seat to prevent flow of gas from said chamber into saidconduit means, a cylindrical valve stem extending from said poppet endportion at the opposite. side thereof and through sai chamber forconnection with valve actuating means, apertured wall means at the otherend of said chamber to slidably receive and guide said valve stem, acoil spring on said valve stem between said apertur'ed wall means andsaid poppet end portion'for biasing said pop-pet valve toward seatedposition, cylindrical flange means extending from said apertured wallmeans around the valve stem guiding aperture therein, an elastic sealingband encircling said cylindrical flange means and a portion of saidvalve stem adjacent thereto, and said valve stem having a diametersubstantially equal to the diameter of said valve seat, whereby the gaspressure against said poppet end portion adjacent to said valve seat andradially outward therefrom when the valve is closed is equalized by thegas pressure against said poppet end portion adjacent to said valve stemand radially outward therefrom.

HENRY SEELER.

REFERENCE S CIT The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

